Sway Ref: Style Guide single use variables (FuelLabs#4664)

docs/reference/src/SUMMARY.md

@@ -71,6 +71,7 @@
   - [Pattern Matching](./documentation/language/style-guide/pattern-matching.md)
   - [Comments](./documentation/language/style-guide/comments.md)
   - [Getter Functions](./documentation/language/style-guide/getters.md)
+  - [Intermediate Variables](./documentation/language/style-guide/intermediate-variables.md)
 
 ## Common Operations
 

docs/reference/src/code/Forc.lock

@@ -118,6 +118,14 @@ name = 'interface'
 source = 'member'
 dependencies = ['std']
 
+[[package]]
+name = 'intermediate_variables'
+source = 'member'
+dependencies = [
+    'core',
+    'std',
+]
+
 [[package]]
 name = 'letter_casing'
 source = 'member'

docs/reference/src/code/Forc.toml

@@ -29,6 +29,7 @@ members = [
   "language/style-guide/letter_casing",
   "language/style-guide/pattern_matching",
   "language/style-guide/struct_shorthand",
+  "language/style-guide/intermediate_variables",
   "language/traits/associated-consts",
   "language/variables",
   "misc/advanced-concepts/enum_advanced",

docs/reference/src/code/language/style-guide/intermediate_variables/.gitignore

@@ -0,0 +1,2 @@
+out
+target

docs/reference/src/code/language/style-guide/intermediate_variables/Forc.toml

@@ -0,0 +1,9 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "lib.sw"
+license = "Apache-2.0"
+name = "intermediate_variables"
+
+[dependencies]
+core = { path = "../../../../../../../sway-lib-core" }
+std = { path = "../../../../../../../sway-lib-std" }

docs/reference/src/code/language/style-guide/intermediate_variables/src/lib.sw

@@ -0,0 +1,29 @@
+library;
+
+#[allow(dead_code)]
+fn update_state() -> u64 {
+    // Used for context in the following function
+    42
+}
+
+#[allow(dead_code)]
+// ANCHOR: contextual_assignment
+fn contextual_assignment() {
+    let remaining_amount = update_state();
+    // code that uses `remaining_amount` instead of directly calling `update_state()`
+}
+// ANCHOR_END: contextual_assignment
+
+#[allow(dead_code)]
+fn update_state_of_vault_v3_storage_contract() -> u64 {
+    // Used for context in the following function
+    42
+}
+
+#[allow(dead_code)]
+// ANCHOR: shortened_name
+fn shortened_name() {
+    let remaining_amount = update_state_of_vault_v3_storage_contract();
+    // code that uses `remaining_amount` instead of directly calling `update_state_of_vault_v3_storage_contract()`
+}
+// ANCHOR_END: shortened_name

docs/reference/src/documentation/language/style-guide/intermediate-variables.md

@@ -0,0 +1,19 @@
+# Intermediate Variables
+
+An intermediate variable, or a temporary variable, is a variable that is typically used once. In most cases we avoid creating intermediate variables; however, there are cases where they may enrich the code.
+
+## Contextual Assignment
+
+It may be beneficial to use an intermediate variable to provide context to the reader about the value.
+
+```sway
+{{#include ../../../code/language/style-guide/intermediate_variables/src/lib.sw:contextual_assignment}}
+```
+
+## Shortened Name
+
+In the cases of multiple levels of indentation or overly verbose names it may be beneficial to create an intermediate variable with a shorter name.
+
+```sway
+{{#include ../../../code/language/style-guide/intermediate_variables/src/lib.sw:shortened_name}}
+```